In the 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE) system, both uplink and downlink apply the Multiple Input Multiple Output (MIMO) way. The MIMO system can increase the channel capacity over a plurality of times and has very high spectrum utilization efficiency. However, compared with the Single Input Single Output (SISO) system, the MIMO system might cause the Co-Channel Interference (CCI). The typical techniques for eliminating the CCI include beam forming or pre-encoding at the transmitting end, multi-user detecting at the receiving end, or the joint design of the receiving and the transmitting ends. Since the multi-user detecting at the receiving end is easy to be affected by the error spread, thus using the beam forming or pre-encoding at the transmitting end to eliminate the CCI is more beneficial to the performance.
At present, the joint receiving and the transmitting research based on the channel information known by both the transmitting end and the receiving end is widely focused, for example, the Singular Value Decomposition (SVD) beam forming algorithm. The SVD beam forming algorithm can decompose a MIMO channel into multiple parallel independent SISO sub channels. In the condition that the total transmission power is fixed, using the water-filling algorithm to allocate power can achieve the maximum channel capacity.